Polysaccharides are conventionally used to viscosify water that is used in well completions to enhance the ability of water to transport solids, reduce fluid loss, and to minimize friction losses. Fluid-loss control and solids transport properties are enhanced by the addition of crosslinkers that tie multiple polymer chains together a depicted in FIG. 1. This results in the formation of gel-like fluids and extreme increase in viscosity. In order to form stable gels, it is necessary that the concentration of the polymer be at or above the C* (the critical overlap concentration). Crosslinking process, however, reduces the polymer's ability to suppress friction during pumping operations and in fact often results in increased friction. Optimal friction reduction occurs with high molecular weight, linear polymers.
On the left side of FIG. 1 is a simplified representation of a polysaccharide with single reducing chain ends, wherein the polysaccharide is dispersed or dissolved in an aqueous phase (not represented in the figure). When a crosslinker is added, linking occurs randomly throughout the intermolecular structure as shown on the right side of FIG. 1, resulting in an exponential increase in viscosity and the formation of a gel.